(1) Field of the Invention
This invention relates to a substrate treating apparatus for performing a series of treatments of substrates such as semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for photomasks, and substrates for optical disks (hereinafter called simply “substrates”).
(2) Description of the Related Art
Conventionally, such a substrate treating apparatus is used, for example, in a photolithographic process for forming photoresist film on substrates, exposing the substrates having the photoresist film formed thereon, and developing the exposed substrates.
This apparatus will be described with reference to a plan view shown in FIG. 1. This substrate treating apparatus includes an indexer 103 having a cassette table 101 for receiving a plurality of cassettes C each for containing a plurality of (e.g. 25) wafers W to be treated, or wafers W having been treated in treating modules 104 described hereinafter, and a transport mechanism 108a movable horizontally along the cassettes C for transporting the wafers W between the cassettes C and treating modules 104. The apparatus further includes, besides the treating modules 104, a main substrate transport path 105 along which the wafers W are transported from one treating module 104 to another, and an interface 106 for transferring the wafers W between the treating modules 104 and an external treating apparatus 107.
The external treating apparatus 107 is an apparatus separate from the substrate treating apparatus, and is detachably attached to the interface 106 of the substrate treating apparatus. Where the substrate treating apparatus is designed for resist application and development as noted above, the external treating apparatus 107 is an exposing apparatus for exposing the wafers W.
The substrate treating apparatus further includes a main transport mechanism 108b movable along the main substrate transport path 105, and a transport mechanism 108c movable along a transport path of the interface 106. In addition, a table 109a is disposed at a connection between the indexer 103 and main substrate transport path 105, and a table 109b at a connection between the main substrate transport path 105 and interface 106.
The above substrate treating apparatus performs substrate treatment through the following procedure. The transport mechanism 108a takes one wafer W out of a cassette C containing wafers W to be treated, and transports this wafer W to the table 109a to pass the wafer W to the main transport mechanism 108b. The main transport mechanism 108b, after receiving the wafer W placed on the table 109a, transports the wafer W into each treating module 104 for a predetermined treatment (e.g. resist application) in the treating module 104. Upon completion of each predetermined treatment, the main transport mechanism 108b takes the wafer W out of the treating module 104, and transports the wafer W into another treating module 104 for a next treatment (e.g. heat treatment).
After the series of pre-exposure treatment is completed, the main transport mechanism 108b transports the wafer W treated in the treating modules 104 to the table 109b, and deposits the wafer W on the table 109b to pass the wafer W to the transport mechanism 108c. The transport mechanism 108c receives the wafer W placed on the table 109b and transports the wafer W to the external treating apparatus 107. The transport mechanism 108c loads the wafer W into the external treating apparatus 107 and, after a predetermined treatment (e.g. exposure), takes the wafer W out of the external treating apparatus 107 to transport it to the table 109b. Subsequently, the main transport mechanism 108b transports the wafer W to the treating modules 104 where a series of post-exposure heating and cooling treatment and development is performed. The wafer W having gone through all the treatment is loaded by the transport mechanism 108a into a predetermined cassette C. The cassette C is transported away from the cassette table 101 to complete a series of substrate treatment.
The conventional apparatus having such a construction has the following drawback.
In the conventional substrate treating apparatus, the single main transport mechanism 108b movable along the main substrate transport path 105 transports the wafer W to and from all the processing units 104. Because of its working speed, the main transport mechanism 108b cannot access many processing units 104 within a short time. Consequently, the conventional substrate treating apparatus cannot meet the present-day requirement for improvement in throughput.